1. Field of the Invention
The field of the invention is that of electronic cards which are coming into increasing use.
An electronic card may notably comprise a memory that can be used to store information and that can be interrogated remotely by means of microwave reception and transmission devices capable of being integrated into the card.
2. Description of the Prior Art
Thus a system, comprising an electronic label, for the identification and automatic detection of vehicles has been the object of a French patent application filed under No. 2 691 813. This system enables the interrogation of an electronic label comprising information elements (for example the VIN or Vehicle Identification Number, the number plate of a vehicle, etc.) that can be directly compared with data elements stored in a file (for example VIN numbers and number plate references of stolen vehicles).
In order to ensure the normal operation of such a label and more generally of electronic cards, it may be useful to fit out these cards with indicators of normal operation attesting notably to the fact that the different components integrated into the label are properly connected.
The owner of a vehicle who affixes such a label to the inside of his windshield will be able to make his own visual checks on the normal operation of all the electronic circuitry and ascertain that, in this way, the vehicle would actually be detected in the event of theft.
When used in a system for the automatic detection of stolen vehicles, the device can inform the legitimate owner that his non-functioning label has to be changed and can provide policemen with visual information on the fact that the vehicle needs to be checked, either because the vehicle does not have a label or because the label is malfunctioning.
Along with this system using electronic labels, there are many electronic systems having light indicators that enable visual checks on normal operation.
However, presently used devices have several drawbacks that need to be emphasized:
the light indicators consume power and are difficult to use on portable systems; PA1 the light indicators are individual components that have to be connected to the system, and their space requirement is such that they cannot be incorporated into very fine systems of the microprocessor-based credit card type.